1. Field of the Invention
The present invention relates to a substrate processing apparatus which processes a plurality of substrates such as semiconductor substrates, glass substrates for liquid crystal display devices, glass substrates for photomasks, substrates for optical disks and the like in succession.
2. Description of the Background Art
As is well known, semiconductor and liquid crystal display products and the like are fabricated by performing a series of processes including cleaning, resist coating, exposure, development, etching, interlayer insulation film formation, heat treatment, dicing and the like on the above-mentioned substrates. In general, a substrate processing apparatus is constructed by incorporating processing units which perform these various processes and transport robots which transport substrates to the processing units in the substrate processing apparatus. An apparatus which incorporates a resist coating unit for performing a resist coating process on a substrate, a development processing unit for performing a development process on a substrate, and a transport robot for transporting a substrate between the coating processing unit and the development processing unit is widely used as a so-called coater-and-developer.
As an example of such substrate processing apparatuses, a coater-and-developer in which a plurality of cells each composed of a single transport robot and a plurality of processing units to and from which the single transport robot transports substrates are provided in juxtaposition and a substrate transfer part is provided between the cells to transfer substrates between the transport robots of adjacent ones of the cells is disclosed, for example, in Japanese Patent Application Laid-Open No. 2005-93653.
The apparatus disclosed in Japanese Patent Application Laid-Open No. 2005-93653 is an apparatus for performing the resist coating process and the development process on substrates. It is, however, conceivable that a structure which connects a plurality of cells through a substrate transfer part in a manner similar to the disclosed apparatus is applied to an apparatus which performs other types of processes, e.g., a cleaning processing apparatus which uses a brush to clean a substrate. Specifically, the cleaning processing apparatus is constructed by connecting an indexer cell which accumulates unprocessed substrates and processed substrates therein and a cleaning processing cell provided with a brush cleaning unit to each other through the substrate transfer part. Each of the indexer cell and the cleaning processing cell is provided with a transport robot exclusive to each cell.
As compared with the coater-and-developer as disclosed in Japanese Patent Application Laid-Open No. 2005-93653, however, the cleaning processing apparatus has short cycle time so that an unprocessed substrate transferred from the indexer cell to the cleaning processing cell is subjected to the cleaning process and returned to the indexer block for a very short period of time. Thus, the entire throughput of the cleaning processing apparatus is often determined by processing time in the indexer.
For the purpose of improving the throughput, it is hence necessary to increase the processing speed of the indexer cell. Specifically, it is conceivable to increase the operating speed of a transport mechanism in the indexer cell. However, only the increase in the operating speed of the transport mechanism causes a problem such that it is difficult to transport substrates with stability at an excessively high speed.